Dressing apparatus



P 1967 A. HOHLER ET AL 3,339,538

DRESSING APPARATUS Filed Nov. 23, 1964 FIG.

FREDERICK A. HOHLER GORDON B RULE INVENTORS.

Y ,Jn-I 'QIT' United States Patent M 3,339,538 DRESSING APPARATUS Frederick A. Hohler, Holden, and Gordon B. Rule, Shrewbury, Mass., assignors to The Heald Machine Company, Worcester, Mass., a corporation of Delaware Filed Nov. 23, 1964, Ser. No. 413,019 3 Claims. (Cl. 125-11) This invention relates to a dressing apparatus and, more particularly, to apparatus arranged to renew and form the surface of an abrasive wheel in a grinding machine.

In the operation of grinding machines, it is common practice to mount the dressing diamond on a holder which can be advanced transversely of the wheel axis and which can be rotated from time to time to assure that the diamond is worn evenly on all sides to give a conical shape. In the past, however, the dressing apparatus incorporating these features have suffered from a number of defects. One of these is that the holder tends to rotate by itself in a more or less erratic manner, so that the diamond is not worn evenly resulting in a high spot on the diamond which causes missizing of the wheel and, of course, of the dimensions of the finished workpiece. Furthermore, most diamond holders which incorporate these features are quite expensive and commonly get out of repair and adjustment in the rugged conditions associated with production grinding. These and other difliculties experienced with the prior art devices have been obviated in a novel manner by the present invention;

It is, therefore, an outstanding object of the invention to provide aj'dressing apparatus in which the rotation and advancement of the diamond takes place in a positive controlled manner. j"

Another object of this invention is the provision of a dressing apparatus 'in which the diamond holder is not permitted to rotate except when permitted to do so at a-controlled rate for a controlled amount by the apparatus.

A'further object of the present invention is the provision of a dressing apparatus which is simple in construction, inexpensive to manufacture and which is capable of along life of useful service with a minimum of maintenance.

With these and other objects in view, as will be apparent to those skilled inthe art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

The character of the invention, however, may be best understood by reference to one of its structural forms as illustrated by the accompanying drawings in which:

FIG. 1 is a vertical sectional view of the invention taken on the line II of FIG. 2, and

FIG. 2 is a vertical sectional view of the invention taken on the line IIII of FIG. 1.

Referring to the drawings, it can be seen that the dressing apparatus, indicated generally by the reference numeral 10, consists of a body 11, in which is mounted a diamond holder 12 carrying on its outer end a diamond 13. Extending through the body 11 in the intermediate portion is a horizontal bore 14. The bore is provided with a reduced cylindrical portion 15 in which is slidably and rotatably carried a cylindrical portion 16 of the holder, the cylindrical portion being interrupted by a groove carrying a seal 17. The end of the holder 12 which carries the diamond 13 protrudes from the bore 14 and from the reduced portion 15 and is provided with a longitudinal socket 18 which carries a nib 19 on which the diamond 13 is mounted. The nib is held in place in the socket 18 by a set screw 21. The bore 14 is formed adjacent the reduced portion 15 with an internal conical portion 22 and the holder is provided with an external conical portion 23 of exactly the same configuration and I 3,339,538 Patented Sept. 5, 1967 slope, so that the two conical portions fit together tightly on occasion. The conical portion 22 of the bore 14 merges into an enlarged cylindrical portion 24 and this portion extends to the outer surface of the body 11. Mounted on the 'body and overlying the opening of the enlarged portion 24 to the outside is a head 25 which is bolted to the outside of the body. The head is provided with a nose 26 which slides tightly into the enlarged portion 24 of the bore and is provided with an internal bore 27. The diamond-holder 12 is provided with a cylindrical portion which slides smoothly and tightly in the bore 27 and is' provided with a groove carrying a seal 28, the holder and the head 25 operating as a hydraulic cylinder in this area. Extending from the end of the bore 27 is a port 29 to which is connected a hydraulic line 31. Extending vertically through the body 11 is a bore 32 whose axis is located well to one side of the axis of the bore 14 and in the bore 32 is carried a piston 33. Pivoted to the lower end of the piston is a pawl 34 having a lower end which engages on occasion the teeth of a ratchet 35. The pawl is provided with an upwardly-extending finger 36 which is engaged by a slide 37. The slide 37 is pressed toward the finger 36 by a coil spring 38 mounted with the slide 37 in a horizontal bore 39 carried in a bolt-like member 41 mounted in a threaded bore 42 entering the side of the body 11. A set screw 43 is t-hreadedly engaged with the member 41 in the bore 39 to provide for adjustment of the tension in the spring 38. At its upper end, the bore 32 is provided with an enlarged portion 44 and in this enlarged portion is carried a piston 45 which is fixed to the piston 33. Bolted to the top of the body 11 and overlying the bore 33 and its enlarged portion 44 is a head 46 which is provided with a port 47 communicating with the upper part of the enlarged portion 44 and connected to a hydraulic line 48. Extending from the lower portion of the enlarged portion 44 through the body 11 is a passage 49 Which connects with a similar passage 51 extending through the head 25, the passage 51 communicating with the port 29 and, therefore, with the hydraulic line 31. The hydraulic lines 48 and 31 are connected to the output ports 52 and 53 of a solenoid valve 54. The valve also has a pressure port 55 connected by a conduit 56 to a pump 57. The pump receives its input oil from a sump 58 and the valve 54 is provided with two drain ports 59 and 61 which are connected by a conduit 62 to the sump 58. Slidable in the valve is a valve spool 63 which operates in the usual way to connect the various ports to one another on occasion. Extending from the spool is a plunger 64 which extends through and is operated by an electrical coil 65 connected in the usual way to the controls of a grinding machine. The spool 63 occupies one of two positions. In the position shown in the drawing, the spool connects the pressure port 55 to the output port 53. At the same time, it connects the output port 52 with the drain port 59. In the other position, the spool 63 connects the pressure port 55 with the output port 52 and connects the output port 53 with the drain port 61. r

The operation of the apparatus will now be readily understood in view of the above description. When the solenoid valve 54 is in the position shown in the drawings, the pressure oil from the pump 57 flows through the conduit 56 to the pressure port 55 of the valve, around the spool 63 and out through the outlet port 53 and the hydraulic line 31 to the port 29 of the dressing apparatus. In this position, the oil presses against the outer end of the diamond holder 12 and it acts as a hydraulic cylinder or linear actuator. In this condition, the conical surfaces 22 and 23 are pressed tightly together and this prevents the diamond holder from rotating in the bore 14. At the same time, the pressure oil leaves the port 29, passes up wardly through the passage 51 and the passage 49 to the underside of the piston 45 in the enlarged portion 44 of 6? the bore 32. This oil presses upwardly on the piston and causes the piston and its connected piston 33 to move upwardly in the bore, eventually, reaching the upper end of the bore and engaging the head 46, which is its upper limiting point. The upper end of the enlarged portion 44 above the piston 45 is connected through the port 47 and the hydraulic line 48 to the port 52 of the valve 54. At this time, the valve 54 connects the port 52 around the spool 63 to the drain port 59 so that oil is pressed outwardly in this way through the hydraulic line 62 to the sump 58. The finger 36 of the pawl 34 is provided with an elongated fiat portion for engagement at all times by the slide 37, despite the fact that the pawl is moving up and down with the piston 33.

On receipt of a signal by the coil 65 the plunger 64 is drawn to the left so that the pressure port 55 is connected to the output port 52 of the valve and pressure oil flows through the hydraulic line 48 and the port 47 to the upper side of the piston 45, pushing it downwardly. At the same time, the port 53 of the valve is connected to the drain port 61 so that the oil passes through the valve and the drain line 62 to the sump 58. This means that the oil is easily pressed from the underside of the piston 45 and, furthermore, there is no pressure oil on the end of the diamond holder 12. This means that the conical surfaces 22 and 23 are not held together and the diamond holder is free to rotate. The piston 45 moving downwardly with the piston 33 carries the pawl 34 into engagement with a tooth of the ratchet 35, thus rotating the diamond holder and producing a slight turning of the diamond relative to the abrasive wheel.

In a preferred embodiment of the invention, the pressure oil supplied by the pump 57 was at 500 pounds per square inch, so that when the outer end of the diamond holder 12 which resides in the bore 27 had an area of .2485 square inch, the force pressing the diamond holder to the left so that the conical surfaces 22 and 23 are engaged, was 124.25 lbs. The ratchet 35 was provided with 16 teeth equally spaced at 22 /2 and this, of course, resulted in a similar rotation of the diamond 13. The stroke of the piston 45 was selected at .144 inch to produce the incremental movement of the ratchet 35. The elfective area of the piston 45 on the underside was .214 square inch so that with 500 pounds p.s.i. oil this gave a total of 103 pounds upward thrust carrying the pawl upwardly. In the downward direction, the top of the piston 45 had an area of .3062, so that with 500 pounds oil this gave 153 pounds pressing downwardly and producing the rotation of the diamond holder. The diamond nib 19 was threaded into the socket 18 so that when the set screw 21 was loosened it was possible to adjust the nib back and forth by .045 inch, if necessary.

It can be seen, then, that the present invention provides for rotation of the diamond by fixed incremental amounts and for assuring that the diamond holder does not rotate between incremental rotations. The apparatus is simple and makes use of conventional equipment incorporated into the grinding machine.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is:

1. Dressing apparatus for a grinding machine, comprising (a) a body having a bore,

(b) a diamond holder rotatably mounted in the bore and having a cylindrical portion which engages a correspondingly cylindrical portion of the bore,

(c) a first hydraulic cylinder for turning the holder relative to the body by producing incremental unidirectional rotation of the holder, and

(d) locking means including a second hydraulic cylinder for preventing rotation of the holder on occasion, the bore being provided with an internal conical surface and the holder being provided with an external conical surface, the second hydraulic cylinder pressing the conical surfaces together on occasion to prevent relative rotation between the holder and the body.

2. Dressing apparatus as recited in claim 1, wherein the first hydraulic cylinder reciprocates a pawl which engages a ratchet on the holder.

3. Dressing apparatus as recited in claim 2, wherein a valve serves to connect pressure fluid or drain alternately to the first and second cylinders.

References Cited UNITED STATES PATENTS 2,581,544 1/1952 Loecy -11 2,644,442 7/1953 Loecy 12511 2,648,171 8/1953 Hill.

2,860,622 11/1958 Hider 12511 2,934,978 5/ 1960 Estabrook 77-64 XR 2,999,493 9/1961 Blair 12511 HAROLD D. WHITEHEAD, Primary Examiner, 

1. DRESSING APPARATUS FOR A GRINDING MACHINE, COMPRISING (A) A BODY HAVING A BORE, (B) A DIAMOND HOLDER ROTATABLY MOUNTED IN THE BORE AND HAVING A CYLINDRICAL PORTION WHICH ENGAGES A CORRESPONDINGLY CYLINDRICAL PORTION OF THE BORE, (C) A FIRST HYDRAULIC CYLINDER FOR TURNING THE HOLDER RELATIVE TO THE BODY BY PRODUCING INCREMENTAL UNIDIRECTIONAL ROTATION OF THE HOLDER, AND (D) LOCKING MEANS INCLUDING A SECOND HYDRAULIC CYLINDER FOR PREVENTING ROTATION OF THE HOLDER ON OCCASION, THE BORE BEING PROVIDED WITH AN INTERNAL CONICAL SURFACE AND THE HOLDER BEING PROVIDED WITH AN EXTERNAL CONICAL SURFACE, THE SECOND HYDRAULIC CYLINDER PRESSING THE CONICAL SURFACES TOGETHER ON OCCASION TO PREVENT RELATIVE ROTATION BETWEEN THE HOLDER AND THE BODY. 